What size Electric Combi Boiler do I need? - A Guide
Choosing an appropriately sized Electric Combi Boiler can be a tedious and frustrating process – the gradual switchover from gas-based energies has left many people in need of a simple answer to the question: What kW Electrical Combi Boiler would I need? We aim to offer guidance here for the implementation of Electrical Combi Boilers from smaller to larger properties, you’ll need a unique consideration based on your actual property's individual characteristics and usage demands.
Briefly before moving forward, Gas-Based Combi Boilers often offer a much higher actual kilowatt Output than their electrical equivalents. The returns ratio on gas vs electrically fuelled system do unfortunately mean that the ceiling for an electric combi boiler sits around the 2/3 bedroom household mark, at least if we were aiming to discuss whole household solutions through one Combi Boiler. Therefore, a consumer should adjust their expectations accordingly, and Plumbers should be competent to verify these issues and confirm the suitability of the recommendations that shall follow. When Specifying an Electric Combi Boiler, we would always use the general rule of thumb to offer 1.5kW of heating for every 1 radiator. (Source Material's Linked Here) This might buffer up to a .5kW extra needed if, for example, the household was single-glazed, or had particularly high ceilings.
What’s a good Electric Combi Boiler for my 1 bed Flat?
We definitely have a few great options here to consider. Most 1 Bedroom flats are likely to have 6 or fewer radiators if powered via Electric Combi Boiler. We can imagine at least 1 user, with a shower, to an estimated maximum 2 users, with a bath. Thus, there are a few really great options to consider at this slightly smaller scale of use. One great option we would offer is the Trianco 8kW mini combi boiler. This would be a neat and appropriate installation for a 4 radiator, 1 shower no bath usage. The perfect fit for efficiency for a single user! the 8kW with water storage - offered here - would essentially offer a small hot water reserve, allowing the 4 radiators flat to cater to a second user/bath potential as well, though note this would sit on the budget side with this recommendation!
4 radiators: 0 Baths: 1 User: Trianco 8kW Mini Electric Combi Boiler
4-6 Radiators: up to 1 Bath/shower unit: 1-2 Users: Trianco 8kW Maxi Electric Combi boiler with Water Storage: EHC 12kW Astro Combination Boiler
What’s a good Electric Combi Boiler for my 2 Bedroom/3 bedroom Household?
When we get to this scale of a property, the various options really open up for the user, many brands can be considered, and various competitors exist in this scale market. If you’re seeking to save money / cut down on costs, We'd advise looking to the 10 to 12 Kilowatt ranges, which should be strong enough for 6-8 Radiators. Then, I'd look to up the kilowattage / offer the additional storage where bathing is required, or for future proofing your solution! What works right now might not in future if you're considering expanding the family or the property. As the radiators or baths exceed the 10 radiators or 2 bath marks respectively, we begin to see the maximum realistic achievable outputs of these units for Single phase Domestic Use.
So, for a 2 Bedroom small household, of 2-4 people, we could suggest something like the 10kW with water storage from Trianco, moving up to 12kW with water storage or 14.4kW without as we move to the larger 3-bed property. The usage of water storage may be inconvenient, but when aiming to power a bath comparative to a shower, the small 38L storage that Trianco offer really provides a great benefit and quality to the unit when baths / larger "at once" water draws are required. We begin to reach the maximum power outputs here at the 12kW with Water Storage, or 14.4kW without here. This does unfortunately leave the question...
What if I'd like to expand past this? What Combi-Boilers would suit a larger property? How can I decide?
Where it comes to any scale past the 2-to-3-bedroom requirements, I personally would begin to look to suggest alternative methods of heating your household. At this scale, you would likely begin to look into Three Phase or Commercially wiring an Electric Combi Boiler, which is often electrically unachievable and can begin to become incredibly expensive. For a single unit, in single phase power, we would suggest the top end of performance sits at the ~ 1.5 -2 bath an hour, 8 to 10 Radiators kind of area. For any demand past this, or roughly past the 5-6 user mark, we would begin to strongly advise a system / electric boiler and Cylinder combination. Where 2 bathrooms are in use, Electric Combi Unit's simply aren’t capable at domestic energy to power these baths simultaneously. For larger usage households, we could begin to suggest the same 1.5 rads to 1kW ratio, then usage of an indirect cylinder could allow for secondary coil-based heating of the household hot water – this would require a larger space, yet would be able to offer mains pressure water to the larger usage household, likely at a fraction of the cost the Combi Boiler would run up to. This would be one of the most effective and efficient means to assist, though you could use the aforementioned combi boiler S plan configuration, using the combi boiler to power the radiators and part of the water demands, with an alternative water storage unit / Direct Hot Water cylinder to power and provide the storage water for the additional usages, this might be a nifty solution for a household with reduced radiator / increased Hot Water usage proportions – though please ensure a plumber approves this method before employment! For more on S plan configuration - read here
Conclusion
You can of course, always use the wonderful Help Me Choose My tools alongside this article to absolutely pinpoint your desired unit, between this guide and the HMCM Pages we aim to provide clarity and understanding to the consumer base, with the best possible rates and service to business customers. Check us out on Trustpilot, or give us a call at 01934 253600 to order now or enquire - from consideration to installation, Electrical Deals Direct.
